Speed-indicating device



June 12, 1934. G. w. TONEY SPEED INDICATING DEVICE Filed March 1, 1952 indicating device embodying the Patented June 12, 1934 UNITED STATES SPEED-INDICATING DEVICE George W. Toney, Waltham, Mass., assi nor to Waltham Watch Company, Waltham, Mass., a corporation of Massachusetts Application March 1, 1932, Serial No. 596,140

9 Claims.

This invention relates to magnetic speed indicating devices, and especially automobile speedometers, wherein a magnet that rotates at a speed that is proportional to the car speed acts electromagnetically through a small intervening air gap upon a pivoted conducting member, as an aluminum disc, to displace the disc from a zero position into positions proportional to the speed of the magnet and against the action of a restraining spring which, when the magnet is stationary, holds the disc in a rest or zero position.

Under some conditions the speed-indicating member exhibits some reluctance to movement away from zero position immediately when the car begins to move and remains in zero position until the car speed has increased sufficiently for the drag of the rotating magnet on the member to overcome the starting resistance of the latter. After the indicating member is once away from zero position it will respond faithfully to variations in speed of the driving magnet.

It is an object of the present invention to overcome the starting resistance of the speed-indicating member and to condition it for instant response to the initial movement of the driving magnet.

Specifically, this object of the invention is obtained by causing the speed-indicating member, when at zero position, to bear against a yielding vibratory. member that is so flexible that the speed-indicating device is capable of vibrating or oscillating slightly in response to the vibration of the running automobile engine, or to the vibration caused by a passenger entering the car, even though these vibrations are small. The starting friction between the speed-indicating member and its bearings is thereby broken so that the member is in condition to respond instantly to the movement of the driving magnet. Such a construction constitutes a further object of the invention.

A yet further object is generally to improve the construction and operation of speed-indicating and responsive devices.

Fig. 1 is a sectional elevation through a speed present invention.

Fig. 2 is a perspective detail, partly in section, of the device of Fig. 1.

Fig. 3 is a plan view of the driving magnet, taken along line 3-3 of Fig. 1.

Fig. 4 is a plan view of the speed-indicating disc and the yielding vibrating stop therefor, taken along line 4-4 of Fig. 1.

Fig. 5 is a plan detail of the restraining spring of the speed-indicating disc, taken along line 5-5 of Fig. 1.

The speed-indicating device, or speedometer, that incorporates the present invention comprises a die-cast frame 10 having a bottom wall 12 and a boss 14 projecting from the bottom wall.

A steel drive shaft 16 is journalled in the wall and boss and terminates in a square end 18 located in, a screw-threaded recess 20 of the boss for attachment to some driving member, usually a flexible shaft, not shown. A collar 22 is fixed to the shaft in an upper reduced portion of the recess and is adapted to engage a fibre washer 24 which encircles the shaft loosely between said collar and the end wall of said recess for the purpose of limiting axial movement of the shaft in one direction. The upper end of the shaft ispassed loosely through a steel cup 26 carried by the frame and having a radial upper face. Said shaft terminates in a reduced upper end 28 immediately above said cup and has a brass hub 30 fixed on said reduced end and seated upon the shoulder between said reduced end and the body of the shaft. Said hub is provided at its lower end with a radially-outstanding flange 32 which overlies said cup 26 and so prevents movement of the shaft in a downward direction. A fibre washer 34 is located between the flange and cup to support the rotating hub.

A driving magnet comprising a flat hardenedsteel disc 36 having a radial slot 38 providing opposed poles 40 is fixed upon said hub 30 concentrically with said shaft and is seated upon said hub-flange 32 and thus is constrained to rotate with the shaft. An armature comprising a fiat soft iron disc 42 corresponding generally in diameter to that of the magnet disc and havinga central aperture 44 and opposed radiallyoutstanding ears 46 is located in relatively closely spaced relation above and concentric with the magnet disc and has its ears seated upon shelves 48 of the frame 10 and secured removably thereto by screws 50.

A speed-responsive device, or rotor, comprising a flat disc 52 of a material, as aluminum, having good electrical conductivity, and having a diameter approximately equal to the diameter of the driving magnet, is located in the air gap between the magnet and armature and parallel to both. Said disc is clamped to a hub 54 between opposed flange-plates 56 which are fixed to said hub; and said hub is fixed to a vertical steel shaft 58. Said shaft is provided with a reduced lower end 60 that is located in an axial recess in the upper end of the driving shaft 16 and has a pivotal seat on a hardened-steel plate 62 contained in a cup 64 located in the bottom of said recess. The upper end of said shaft also has a reduced end 66 which is journalled in a bearing bushing 68 that is screw-threaded in a supporting plate '70 carried by upstanding posts 72 of the frame 10. The bushing is axially adjustable in said plate to restrict end play of the shaft 58 and is locked in adjusted position by a check nut 74. Rotation of the shaft and disc in one direction is opposed by a light spiral spring 76 one end of which is fixed to the shaft 58 and the other end of which is secured adjustably in a plate '78 clamped under the check nut 74. The upper end of the shaft 58 passes through a dial plate and has an indicating hand 82 thereon that is movable over the dial and the speed-indicia 84 thereof to indicate the speed at any instant.

When the driving magnet is stationary, the spring '76 returns the disc and the hand connected therewith to a zero or rest position wherean upstanding lug 86, that is struck out of the disc on one side of the shaft 58 and is located in the aperture 44 of the armature 42, can be against an inwardly-projecting lug 88 of the armature.

As heretofore stated, under some conditions the disc exhibits a reluctance to move away from zero position until the speed of the magnet is sufficiently high to overcome the starting resistance of the disc. This is apparently due to oil or dust as it does not exist if the parts are absolutely clean. In accordance with the present invention this situation is eliminated by supporting the lug 86 of the disc against a resilient and vibratile stop, rather than against the rigid unyielding lug 88. Said resilient stop comprises a slender springy wire 90 that is located on one side only of the pivot shaft 58 and one end of which is secured by a wedge 92 or otherwise in an aper ture in a frame post '72 and the free end of which extends inwardly over the armature 42 and is terminated just forwardly, that is to say, angularly forwardly in the direction of rotation, of the forward face of the armature lug 88 and there is engaged by the lug 86 of the disc in the Zero position thereof due to the action of the spring 76. The wire 90 is thin and slender and is adapted to be flexed somewhat by the pressure of the disc thereagainst although not so much as ordinarily to permit the lugs 86 and 88 to engage except when the magnet 40 is reversely rotated by the reverse movement of the automobile, when the engagement of the lugs holds the disc from being driven backward. Thus when the disc is stationary it is held in balance with the spring '76 urging it slightly backwards and the spring wire 90 urging it slightly forwards. The characteristics of the wire are so chosen that it is caused to vibrate, when the disc is thereagainst, in the direction of rotation of the disc in response to a jar on the frame 10, such as is caused by a passenger entering the automobile, by the vibration of the running engine, or the like. While the disc 52, in its zero position, is rotatively balanced by the two springs 90 and '76, one end of the spring 90 is so positioned, and is supported at one end, that the vibration of the instrument causes the vibration of the end of the spring. Hence such vibration, acting on one side only of the disc, causes the disc to vibrate or tremble slightly in zero position, but sufficiently so that the starting friction of the disc is overcome and the disc is caused to respond instantly to the starting in rotation of the magnet.

I claim:

1. A speed indicator having a driving magnet, a speed-indicating member driven by said magnet, and vibratile means responsive to the vibration of the indicator and acting on said member in the direction of speed-indicating movement when it is at rest to overcome the starting resistance thereof so that it can move away from rest position in instant response to the movement of said magnet.

2. A speed indicator having a driving magnet, a speed-indicating member driven by said magnet, and vibration-responsive means actuated by the vibration of the indicator and acting on said member inv the direction of speed-indicating movement when it is at rest to overcome the starting resistance thereof and to aid it to move away from rest position in instant response to the movement of said magnet.

3. A speed indicator having a driving magnet, a speed-indicating member driven by said magnet away from a rest position into positions dependent upon the speed of said magnet, and vibratory means actuated by the vibration of the indicator which causes said member to vibrate in the direction in which it is adapted to be driven when it is in rest position, whereby to overcome its starting resistance.

4. A speed indicator having a driving magnet, a speed-responsive member driven by said magnet away from a rest position into positions dependent upon the speed of said magnet, a spring which opposes movement of said member away from a rest position, and a vibratile support against which said member is held in rest position, said vibratile support being responsive to the vibration of the indicator and capable of causing said member to vibrate in its rest position in the direction in which it is adapted to be driven to such an extent as to reduce its starting resistance so that it can respond instantly to the starting in motion of said magnet.

5. A speed indicator having a driving magnet, a pivoted speed-responsive disc driven by said magnet away from a rest position into positions dependent upon the speed of said magnet, a spring which opposes movement of said member away from rest position, said disc having a lug on one side or" its center, and a thin and slender resilient and vibratile member which has a fixed support for one end and is otherwise free and unsupported and has its free end loosely engaged and flexed by said lug when said disc is in rest position, said resilient member being responsive to vibration of the indicator and causing said disc to vibrate when it is in rest position and of reducing its starting resistance so that it can respond instantly to the starting in motion of said magnet.

6. A speed indicator comprising a magnetized rotatable disc constituting a driving magnet, a fixed disc disposed in parallel spaced relation with said magnet and constituting an armature therefor, a speed-indicating disc located between and parallel with said magnet and armature and rotatable by said rotating magnet away from a rest position into positions dependent upon the speed of said magnet, a spring which opposes rotation of said speed-indicating disc away from rest position, said speed-indicating disc having a lug at one side of its center, and a thin and slender resilient and vibratile member which has a fixed support for one end and is otherwise free and unsupported and has its free end loosely engaged by said lug when said disc is in rest position and responsive to vibration of the indicator to cause said speed-indicating disc to vibrate when it is in rest position and thereby to reduce its starting resistance so that it can respond instantly to the starting in rotation of said magnet.

'7. A speed indicator comprising a magnetized rotatable disc constituting a driving magnet, a fixed disc disposed in parallel spaced relation with said magnet and constituting an armature therefor, a speed-indicating disc located between and parallel with said magnet and armature and rotatable by said rotating magnet away from a rest position into positions dependent upon the speed of said magnet, a spring which opposes rotation of said speed-indicating disc away from rest position, said speed-indicating disc having a lug at one side of its center which projects through an aperture in said armature, and a thin and slender resilient and vibratile member which has a fixed support for its outer end and is otherwise tree and unsupported and has its free end overlying said armature and engaged by said lug when said speed-indicating disc is in rest position, said member being responsive to vibration of the indicator to vibrate said speed-indicating disc when it is engaged therewith and to reduce its starting resistance so that it can respond instantly to the starting in rotation of said magnet.

8. A speed indicator comprising a rotatable shaft, a magnetized disc comprising a driving magnet fixed to said shaft, a fixed disc disposed in spaced parallel relation with said magnet and constituting an armature therefor, a speed-indicating disc located between and parallel with said magnet and armature and adapted to be rotated by said magnet away from a rest position into positions dependent upon the speed of said magnet, a rotatable shaft which carries said speedindicating disc and has a pivotal support at one end on said magnet-shaft and a second pivotal support above said armature, a spring which is connected with said disc-shaft and which opposes movement of said disc away from the rest position, and resilient and vibratile means loosely engaged by said speed-indicating disc on one side of the pivotal support for said disc when it is in rest position and responsive to vibration of the indicator for causing said disc to vibrate and thereby reduce its resistance to starting in response to the starting in motion of said magnet.

9. A speed indicator comprising a rotatable shaft, a magnetized disc comprising a driving magnet fixed to said shaft, a fixed disc disposed in spaced parallel relation with said magnet and constituting an armature therefor, a speed-indicating disc located between and parallel with said magnet and armature and. adapted to be rotated by said magnet away from a rest position into positions dependent upon the speed of said magnet, a rotatable shaft which carries said speedindicating disc and has a pivotal support at one end on said magnet-shaft and a second pivotal support above said armature, a spring which is connected with said disc-shaft and which opposes movement of said disc away from the rest position, and a thin and slender spring wire which has a fixed support for one end thereof and is otherwise free and unsupported and is located in position to be engaged loosely by a peripheral part of said speed-indicating disc when it is in rest position, said wire being responsive to vibration of the indicator and capable of vibrating said disc and of reducing its starting resistance so that it is responsive to the starting in rotation of said magnet.

GEORGE W. TONEY. 

